/**
 * Permutation.
 *
 * <p>Exchange based permutation.
 *
 * <p>Recursive approach. Given
 *
 *
 * 
 * <pre>
 *   ───┬──────────────
 *   ───┴──────────────
 * </pre>
 *
 * @see <a href="http://homepage.math.uiowa.edu/~goodman/22m150.dir/2007/Permutation%20Generation%20Methods.pdf">Sedgewick (1977) Permutation Generation Methods</a>
 */
package net.tp.algo.permute;
